Abstract:
Objectives: Evaluation of degree of conversion (DC), flexural properties, micro-hardness and color change (ΔE00)
of dental resin composite after modification with two types of organo-modified Montmorillonite (MMT) nano-
clay; an experimentally synthesized polymethyl-methacrylate modified MMT nanoclay (PMMA/MMT), and a
commercially available one (Cloisite20A).
Methods: MMT was synthesized by sol-gel technique, organo-modified with polymethyl-methacrylate and char-
acterized using EDX, XRD and FTIR. PMMA/MMT and Cloisite20A nanoclay were added to flowable resin
composite in 0.5, 1 and 1.5 wt% concentrations. Unmodified resin composite was used as control group. DC was
assessed by FTIR, flexural properties were tested by three-point bending test using a universal testing machine,
micro-hardness was analyzed by Vickers micro-hardness tester and color change (ΔE00) was evaluated using a
reflective spectrophotometer. SEM and elemental mapping assessment were performed to evaluate nanoclay
distribution in resin composite. Data were analyzed using One-way ANOVA followed by Tukey’s post hoc test, in
addition to Two-way ANOVA (p ≤ 0.05). Weibull analysis was used to analyze flexural strength results.
Results: Characterization results revealed successful preparation of PMMA/MMT. DC results showed insignificant
difference up to 1 wt% of nanoclay concentration. Addition of 0.5 wt% of PMMA/MMT significantly increased
flexural properties, while addition of 1.5 wt% of PMMA/MMT significantly decreased flexural properties. Micro-
hardness results revealed a significant increase in PMMA/MMT groups in all tested concentrations. ΔE00 results
showed that color change was clinically acceptable on adding 0.5 wt% nanoclay.
Conclusion: PMMA/MMT in 0.5 wt% is a promising nanofiller for resin composite that significantly enhanced
flexural strength and micro-hardness without compromising DC and color.
